Field of the Invention
The invention relates to a bed, preferably a hospital or care bed.
The Prior Art
Hospital and care beds typically include a lower frame furnished with drive wheels and an upper frame connected to the lower frame so that the upper frame as a whole can be elevated or tilted, enabling the patient to be positioned head down or head up (Trendelen-burg, anti Trendelenburg position, respectively). The movement is brought about either by means of lifting columns or actuators in connection with a link mechanism. An example of such a bed is for instance known from EP 0 488 582A2 to Huntleigh Technology plc. Altogether, it is definitely dangerous in case a person is directly squeezed in such a construction or indirectly for instance with an implement such as a floor mop. It is also experienced that patients fall out of bed and land on the foot switches, and thereby setting the bed in motion. In order to counter squeezing, the use of contact strips, which cut off the current for the motors, are for instance suggested in DE 198 14 269 to Okin and U.S. Pat. No. 4,534,077 to Martin. JP 2002 125807 to Paramount deals with a bed, where two parallel light sources with corresponding photoelectric cells are mounted under the upper frame, or more specifically at the connection of the link mechanism to the upper frame, and when the light beam is interrupted, the upper frame is stopped, alternatively elevated. In WO 03/088885 A1 to Hill-Rom a number of embodiments for squeeze protection are described based on light carpets and sophisticated positioning of light sources and light receivers.
The present invention relates to the type of squeezing protection, indicated in FIG. 12 of WO 03/088885 A1, where a light source and corresponding receiver are positioned above each side of the lower frame, at its side members. To avoid interference the light sources are located opposite each other on the two side members, so that the light is sent in opposite directions. A further light source and receiver is located at the foot of the bed. These are positioned on the external facade of the traverse, so that they do not collide with the light beams above the side members. As the light source is located on the side of the traverse, it does not provide any direct protection against squeezing from the upper frame. At the bed head of the bed, no protection against squeezing is provided even though hospital and care beds are frequently transported and left standing freely.
The purpose of the invention is to provide a more complete covering squeezing protection of this type.